Learn: exam 1: gluconeogenesis and blood glucose levels

what is gluconeogenesis?

Production of glucose from non-carbohydrate sources

where does gluconeogenesis occur primarily?

liver

what occurs with glucose, insulin, and glucagon levels post-prandial?

what stimulates gluconeogenesis?

1. hours after a meal, blood glucose levels return to baseline

2. glycogen production that was stimulated slows

3. insulin goes up and glucagon goes down

4. glycogenolysis begins in liver

5. gluconeogenesis begins in the liver to maintain blood glucose levels

what are the primary precursors for gluconeogenesis?

amino acids, lactate, glycerol

after days of fasting, what are the rates of the different compounds in the body?

- a huge spike in ketone bodies

- glucose levels remain level

- amino acids spike, decrease, increase again, then decrease again to stop breaking down skeletal muscle

- free fatty acids go up and eventually level out

what is the purpose of ketone bodies in gluconeogenesis?

-provides fuel without breaking down excess protein

-allows for long-term survival without food ingestion

what steps differ in gluconeogenesis from glycolysis?

most steps are the same except the phosphatase enzymes G6P and F-1,6-bisphosphatase

1. alanine and lactate converted to pyruvate

2. pyruvate gets converted into phosphoenolpyruvate

3. on the other side, glycerol gets converted to G3P and then

where does lactate precursors come from for gluconeogenesis?

muscle and RBC

where does glycerol precursors come from for gluconeogenesis?

adipose stores

where do amino acid precursors come from for gluconeogenesis?

skeletal muscle pools

conversion of lactate to pyruvate process?

-catalyzed by lactate DH

-generates NADH

conversion of alanine to pyruvate process?

-catalyzed by alanine aminotransferase

-generates glutamate via alpha-ketoglutarate obtaining an amino group

conversion of glycerol to DHAP process?

-glycerol converted to glycerol-3P via glycerol kinase, generating ADP from ATP

-glycerol-3P converted to DHAP via glycerol-3P DH, producing NADH

conversion of pyruvate to OAA?

-pyruvate converted to OAA in mitochondria

conversion of OAA to PEP?

-occurs in the cytosol

-OAA is converted to PEP via phosphoenolpyruvate carboxylkinase, generating a CO2 and GDP from GTP

how does OAA get across the mitochondrial membrane?

converted to malate and aspartate and back again

explain the conversion of OAA to malate and aspartate to get across the membrane

how is phosphoenolpyruvate converted to glucose?

-in the cytosol

-in stages of 4 steps

how is PEP converted to fructose-1,6-bisphosphate?

1. first step

how is fructose-1,6-bisphosphate converted to fructose-6P?

2. second step

how is fructose-6P converted to G6P?

3. third step, identical to glycolysis

how is G6P converted to glucose?

4. fourth and final step

what else is gluconeogenesis stimulated by?

prolonged exercise, high protein diet, stress

what three sequences in the pathway of gluconeogenesis are regulated?

1. pyruvate to PEP

2. fructose-1,6-bisphosphate to fructose-6P

3. G6P to glucose

how is pyruvate to PEP regulated?

how is G6P to glucose regulated?

what glycolytic enzymes are apart of regulation?

what gluconeogenic enzymes are apart of regulation?